Preparation of the Ganache Cream
Mix two egg yolks with the sugar and whisk until clear and creamy.
Bring the double cream to the boil.
Add the whisked yolks and cook up to 90°C (194°F).
Add the coffee and mix well.
Pour the mixture over the chocolate diced into small pieces.
Mix until the chocolate is completely dissolved.
Chill in the fridge.
Dice the butter into cubes and bring to room temperature.
Form a fountain shape with the flour and cocoa powder.
Place the butter, sugar and egg in the well of the fountain.
Knead the ingredients and then add the flour until the mixture is smooth. Return to the fridge for 1 hour.
Lay the pastry over the base and sides of your baking tin.
Use a fork to prick the crostata base.
Cook in a conventional oven at 180°C (356°F) for 18 minutes.
Leave to cool.
Using a pastry bag pour the lukewarm Ganache Cream over the tart.
Place in the fridge until the cream is completely chilled.
Sprinkle icing sugar and serve.